Aiming at the requirement of high reliability and lean planning for urban medium-voltage distribution network, modularization concept, reliability analysis and comprehensive evaluation methods are proposed. Modular distribution network based on station, room, line and cable is explained. The reliability calculation method based on "component-submodule-module", considering multi-outage and inter-module transfer is proposed. The comprehensive evaluation model of modular distribution network is established in multi-dimension. Considering the small gap of evaluation indexes, an improved entropy weight method is used to carry out the comprehensive evaluation, and an example of a high reliability industrial park is analyzed. The results show that modular design and combination are of great significance for realizing flexible and reliable distribution network.